The present invention relates to glasslike carbon composite materials. More particularly, it relates to a composite material containing glasslike carbon as its main component and having high wear resistance and small coefficient of friction which is highly suitable as a material for precision processed elements.
Various recording/reproduction devices are currently available in the market which use sheets and films having a magnetic layer, or paper as the recording medium. These recording/reproduction devices include a number of elements which either constantly or temporarily come into sliding contact with the recording medium, such as a head slider of a flexible disk, floating slide of a hard disk, a thermal printing head, and a magnetic head. These elements are required to have excellent durability and properties which will not damage the recording medium coming in sliding contact therewith. Moreover, these elements, and the magnetic head in particular, are subjected to super precision processings with accuracies on the order of several microns to several tens of microns. The materials in turn are required to have appropriately superior characteristics for such precision processing.
Silicon dioxides, alumina (aluminum dioxides), silicon carbides, hard glasses, alumina ceramics, ferrites, calcium titanates and barium titanates are commonly used as the material for such elements. Although these materials are suited for precision parts, their hardness and inferior slidability are likely to damage a recording medium. Graphites are known as a material having high slidability characteristics. However, they are highly susceptible to wear and are not stable in maintaining a precise shape over a long period of time. Because of their constituent particles, graphites have insufficient denseness and thus are not suited for use in precision parts.
Various studies were conducted to overcome these defects and found that glasslike carbon is effective in solving the defects. Patent applications have been filed for the findings and laid open as Jap. Pat. Appln. Laid-open Nos. Sho 59-84325 and Sho 59-144019.
Glasslike carbon has an appropriate degree of wearability which, when slid against another material typically used in recording media, becomes worn before the other material is damaged.
Applications have been filed for a method of preparing glasslike carbon having excellent wear resistance. These applications are laid open under the Nos. Sho. 60-171209, Sho 60-131816, Sho 60-171208, Sho 60-171209, Sho 60-171210 and Sho 60-171211.
Upon further experiments, it was found that glasslike carbon may sometimes fail to give sufficient wear resistance when used alone, depending on the surface hardness or coarseness of the materials with which it is contacted.
The present invention aims to provide a composite material for sliding elements that can be used without coating the material with a lubricant or protective film and which:
(1) has small friction resistance against the recording medium material to be contacted with, PA0 (2) would not damage the material to be contacted with, and PA0 (3) is excellent in its wear resistance and durability. PA0 (1) prevents formation of voids during carbonization; PA0 (2) reduces the micropores present in the glasslike carbon material, enabling production of a highly dense composite material with improved wear resistance.